Where does “ābād” come from?

ābād (Old English) comes from Old English ābīdan, from Proto-West Germanic *uʀbīdan.

Ancestry of “ābād”, step by step

Step	Language	Word	Meaning
1	Old English	ābīdan	to abide, wait, remain, delay, remain behind;...
2	Proto-West Germanic	*uʀbīdan	—